1. Field of the Invention
The present invention relates to an ink jet recording apparatus and an ink jet head.
2. Discussion of the Background
Conventionally, an ink jet recording apparatus such as an ink jet printer discharges ink from nozzles as ink droplets by pressurizing ink in an pressure chamber, attaches the ink droplets to a recording medium thereby forms an image.
In this apparatus, ink discharge failure may occur due to clogging in the nozzles or occurrence of bubbles in the pressure chamber. The ink discharge failure causes poor printing on a recording medium.
To solve this problem, a method of providing a filter in an ink supply channel communicating with the pressure chamber has been proposed (See Japanese Published Unexamined Patent Application No. Hei 2-1324). In this method, a filter where a pore size is 0.5 μm or smaller is employed. By using this filter, foreign materials which cause clogging in the nozzles or small particles as cores of bubbles occur in the pressure chamber can be removed, thus the occurrence of discharge failure of water-based ink can be prevented.
However, in a case where pigment ink having an particle diameter of average 100 to 400 nm is used in the ink jet recording apparatus, the filter having the pore size of 0.5 μm or smaller becomes a strong obstruction in the ink flowing through the ink supply channel and delays the speed of filtration of the ink, and as a result, delays the ink supply to the ink jet head, i.e., the pressure chamber. In such case, ink discharge failure may occur.